VMware: VimException __str__ attempts to concatenate string to list

Forces the correct parameter use in VimException and VimFaultException
both exceptions have similar signatures but very different uses. This
change forces a developer to deal with misuse of the exceptions
early in their development cycle (provided the do due dilligence with
their testing.)

Closes-bug: 1287884

Change-Id: I34753382677e3315ea4a71cfe9b3b82e9f9159bb

1 files changed, 9 insertions, 2 deletions

diff --git a/nova/virt/vmwareapi/error_util.py b/nova/virt/vmwareapi/error_util.py
index 44aab09f9b..f04033caf6 100644
--- a/nova/virt/vmwareapi/error_util.py
+++ b/nova/virt/vmwareapi/error_util.py
@@ -38,11 +38,16 @@ class VimException(Exception):
 
     def __init__(self, exception_summary, excep):
         Exception.__init__(self)
-        self.exception_summary = exception_summary
+        if isinstance(exception_summary, list):
+            # we need this to protect against developers using
+            # this method like VimFaultException
+            raise ValueError("exception_summary must not be a list")
+
+        self.exception_summary = str(exception_summary)
         self.exception_obj = excep
 
     def __str__(self):
-        return self.exception_summary + str(self.exception_obj)
+        return self.exception_summary + ": " + str(self.exception_obj)
 
 
 class SessionOverLoadException(VimException):
@@ -65,6 +70,8 @@ class VimFaultException(Exception):
 
     def __init__(self, fault_list, excep):
         Exception.__init__(self)
+        if not isinstance(fault_list, list):
+            raise ValueError("fault_list must be a list")
         self.fault_list = fault_list
         self.exception_obj = excep